Not_a_boffin,
I agree that the additional costs are not credible. You did forget a few items though: -
1/ Project management
1a/ Tea breaks
2/ Transportation
2a/ Tea breaks
3/ Modifications to existing carrier hull and infrastructure
3a/ Tea breaks
4/ Installation of meals
4a/ Guess what?
5/ ITP (instrument and testing plan)
6/ Risk management costs
7/ Project management and team install infrastructure
8/ Cost of all the other dock yard workers who will have to stop what they are doing for a year, and still be paid whilst meals are installed.
Have I forgotten anything?